Abstarct: Free in-plane vibrations of AC electric machine’s stator have been studied. A coupled elastic-electromagnetic model has been utilized, while stator structure modeled as a rotating ring and electromagnetic force modeled with equally spaced rotating springs attached to the interior wall of the ring. Governing equations of motion have been extracted using Hamilton’s principle in conjunction with the classical curved beam theories. The problem cast to the rotating cyclic symmetric ring with moving load. According to the perturbation theory, the general solution assumed to consist of the solution of the corresponding rotating ring problem with a perturbed term arosed from the cyclic symmetry. Vibration problem has been solved analytically and the corresponding natural frequencies and dampings expressed via closed-form exxpressions. Interestingly, cyclic symmetry effect leads to mode splitting phenomenon. The phenomena have been investigated in detail using different spring’s stiffness models, including constant, harmonic time variable and saw tooth models. The results are expected to offer better predictions of the vibrational behavior of the cyclic symmetric ring-shaped structures in general, and in the design of stator of AC electric machines, in particular.